3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <eduma...@google.com>

[ Upstream commit e33d0ba8047b049c9262fdb1fcafb93cb52ceceb ]

Recycling skb always had been very tough...

This time it appears GRO layer can accumulate skb->truesize
adjustments made by drivers when they attach a fragment to skb.

skb_gro_receive() can only subtract from skb->truesize the used part
of a fragment.

I spotted this problem seeing TcpExtPruneCalled and
TcpExtTCPRcvCollapsed that were unexpected with a recent kernel, where
TCP receive window should be sized properly to accept traffic coming
from a driver not overshooting skb->truesize.

Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/core/dev.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4051,6 +4051,7 @@ static void napi_reuse_skb(struct napi_s
        skb->vlan_tci = 0;
        skb->dev = napi->dev;
        skb->skb_iif = 0;
+       skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
 
        napi->skb = skb;
 }


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